Knees made headlines on opening Sunday, never a good thing in the NFL.

Two impact players, Houston middle linebacker Brian Cushing and San Diego wide receiver Keenan Allen, were ruled out for their games Sunday and possibly the remainder of the season.

Allen left the field on a cart after suffering what looked like a serious right knee injury with less than 2 minutes left in the first half. He could be lost for the season, a tough turn of events after Allen returned to play from a kidney injury that kept him off the field last season.

Cushing’s diagnosis was only slightly more optimistic. He also hurt one of his knees but walked off the field under his own power. Cushing also missed significant playing time with a range of injuries in 2012 and 2013, but started every game last season.

Giants linebacker J.T. Thomas III was also carted off, after spraining a knee on a kickoff return on the final play of the first half.

In other injuries, Bucs defensive end Jacquies Smith was carted off the field with a right knee injury and ruled out for the rest of the game against Atlanta. Indianapolis defenders T.J. Green (sprained knee) and Patrick Robinson (medical evaluation) went down in the same series in the first half and stayed out for the rest of the game. Safety Winston Guy (ankle) also left late in the game and did not return.

Detroit’s Theo Riddick left for a while to undergo the concussion protocol, but returned late in the game after being cleared.

In Seattle, rookie running back C.J. Prosise sprained one of his wrists in the first half and wore a protective cast on the sideline, Seahawks coach Pete Carroll said. Dolphins defensive end Mario Williams left the game in the second half to be evaluated for a concussion.


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